The overall objective of the total project is to understand the biochemical mechanism of how the trace mineral selenium causes an increased susceptibility to dental caries. The research will study two facets of selenium-dental caries interaction: a) The deposition of fluoride and selenium into the teeth, bones and soft tissues, and b) The effect of fluoride on selenium toxicity. BIBLIOGRAPHIC REFERENCES: Shearer, T.R. and Ridlington, J.W. Selenium interaction in the hard and soft tissues of the rat. (Submitted to the J. of Nutrition, Sept. 19, 1975). Shearer, T.R. 1975. Interaction of dietary selenium and fluoride in the rat. Fed. Proc. 34, 3989 (abstr.)